1. Field of the Invention
The present invention relates to a coordinate input/detection device detecting coordinates of a pointing instrument such as a pen and a fingertip for inputting or selecting information. More particularly, the present invention relates to an optical coordinate input/detection device detecting coordinates of a pointing instrument such as a pen and a fingertip inserted to a coordinate input area for inputting or selecting information, an electronic blackboard system mainly including the optical coordinate input/detection device, a method of correcting a positioning error of a light-receiving unit included in the optical coordinate input/detection device, and a recording medium storing a program readable by a computer, the program making the computer execute the method.
2. Description of the Related Art
An electronic blackboard device has been known as a device that can read handwriting information written by use of a writing instrument on a writing surface such as a whiteboard or a sheet of paper, by an exclusive scanner, and that can print the handwriting information on a recording sheet by an exclusive printer. Additionally, a recently introduced electronic blackboard system provides a coordinate input/detection device on a writing surface of an electronic blackboard device, thereby enabling input of handwriting information written on the writing surface to a computer such as a personal computer in real time. For example, the Soft Board manufactured by Microfield Graphics, Inc. is a device that enables input of visual data such as a letter or and a picture written on a whiteboard to a computer in real time by including a coordinate input/detection device on the whiteboard. Thus, an electronic blackboard system utilizing the Soft Board can display visual data scanned by the Soft Board on a CRT (Cathode Ray Tube) by inputting the visual data to a computer, can display the visual data on a large-scale screen using a liquid crystal projector, and can print the visual data on a recording sheet by use of a printer. Additionally, such an electronic blackboard system can project an image displayed on a monitor of the computer connected to the Soft Board on the Soft Board by use of the liquid crystal projector, and can operate the computer on the Soft Board.
Additionally, an electronic blackboard system has been introduced, the electronic blackboard system including a display device displaying letters and images, a coordinate input/detection device providing a coordinated input surface, that is, a touch panel, on a top of the display device, and a control device controlling a displaying function of the display device based on an input signal from the coordinate input/detection device, in which the display device and the coordinate input/detection device form a displaying surface and a writing surface of the electronic blackboard system. For example, the Smart 2000 manufactured by SMART Technologies, Inc. inputs handwriting information to a computer by using a coordinate input/detection device as a writing surface provided on a top of a projecting or displaying surface of a panel while projecting image information including letters, pictures, diagrams, graphics on the panel by use of a liquid crystal projector connected to the computer. The Smart 2000, then combines the handwriting information and the image information in the computer, and displays the combined information on the projecting surface in real time through the liquid crystal projector. An electronic blackboard system such as the Smart 2000 and the like can display an image inputted by use of a coordinate input/detection device as a rewriting image on a top of an image being displayed on a monitor of a display device, and thus the electronic blackboard system has already been utilized in wide areas such as a meeting, a presentation and an educational scene, obtaining high evaluation for its effectiveness. Additionally, the electronic blackboard system is also used as an electronic conference system by including a communication function transmitting, for instance, sounds and images, and by connecting remote places with each other by use of communication lines.
Recently, various methods of inputting and detecting coordinates are considered as coordinate input/detection devices utilized in the above-described electronic blackboard systems. A coordinate input/detection device enabling input of information without providing a physical coordinate input surface such as a touch panel, for instance, an optical coordinate input/detection device is considered as one of appropriate coordinate input/detection devices applied to the above-described electronic blackboard systems. One of suggested optical coordinate input/detection devices is an optical coordinate input/detection device disclosed in Japanese Laid-Open Patent Application No. 11-110116. This optical coordinate input/detection device scans a laser beam emitted from a light source provided in each of two optical units by using a polygonal mirror, and reflects the laser beam by use of a retro reflector in a coordinate input/detection area. In a case in which a pointing instrument such as a finger or a pen is inserted to the coordinate input/detection area blocks the laser beam in the area, the optical coordinate input/detection device obtains a pulse number of a pulse motor rotating the polygonal mirror, based on light-intensity distribution at a light-receiving device provided in each of the optical units, calculates an emission angle of the laser beam blocked by pointing instrument corresponding to the pulse number for each optical unit, and determines coordinates of the pointing instrument in the coordinate input/detection area by triangulating the emission angle of the laser beam emitted from each of the optical units. The above-described optical coordinate input/detection device not including a physical surface has high visibility even when equipped on a displaying monitor of a displaying device. In addition, enlargement of the optical coordinate input/detection device is comparatively easy.
Since the above-described optical coordinate input/detection device performs triangulation based on emission angles of blocked laser beams, installation positions (installation angles) of the optical units (the light-receiving devices) are significant. Thus, errors in setting the installation angles should be corrected, based on a contraction rate and the installation positions (the installation angles) that are detected when the optical coordinate input/detection device is powered on, since the optical coordinate input/detection device detects a pointing instrument at incorrect coordinates if the errors occur on the installation positions of the optical units. However, an electronic blackboard system including the optical coordinate input/detection device is often moved being powered in regular operations. During the movement of the electronic blackboard system, adjustment of the optical units is slanted occasionally by vibration and shock caused by hitting the system to an object. Furthermore, the adjustment of the optical units is slanted occasionally by vibration caused by pointing the coordinate input/detection area strongly by the pointing instrument.
Accordingly, it is a general object of the present invention to provide a method and apparatus for preventing misdetection of coordinates of a pointing instrument. A more particular object of the present invention is to provide a coordinate input/detection device, an electronic blackboard system, a method of correcting an error in an installation position (an installation angle) of an optical unit (a light-receiving unit), and a recording medium, by which misdetection of coordinates of a pointing instrument can be prevented, the misdetection being caused by the error in the installation position of the light-receiving unit.
The above-described object of the present invention is achieved by a coordinate input/detection device provided with a coordinate input area, including a light-emitting unit emitting a plurality of rays to the coordinate input area; a light-receiving unit receiving the plurality of rays reflected by sides of the coordinate input area, and obtaining intensity distribution of the plurality of rays; a coordinate detection unit detecting coordinates of a pointing instrument inserted to the coordinate input area, based on the intensity distribution; a standard mark provided at a fixed position in the coordinate input area so that the light-receiving unit generates a peak intensity corresponding to a ray reflected at the standard mark in the intensity distribution; and an error detection unit detecting a positioning error of the light-receiving unit by detecting a shift in a position of the peak intensity in the intensity distribution at fixed timing.
The above-described object of the present invention is also achieved by an electronic blackboard system including an electronic blackboard unit whose displaying surface and writing surface include a displaying unit and a coordinate input/detection unit respectively; and a control unit executing a displaying control of the displaying unit based on a signal outputted from the coordinate input/detection unit, wherein the coordinate input/detection unit includes a coordinate input area corresponding to a displaying surface of the displaying unit; a light-emitting unit emitting a plurality of rays to the coordinate input area; a light-receiving unit receiving the plurality of rays reflected by sides of the coordinate input area, thereby obtaining intensity distribution of the plurality of rays, and outputting the signal corresponding to the intensity distribution; a standard mark provided at a fixed position in the coordinate input area so that the light-receiving unit generates a peak intensity corresponding to a ray reflected at the standard mark in the intensity distribution; a coordinate detection unit detecting coordinates of a pointing instrument inserted to the coordinate input area, in accordance with a position of the peak intensity in the intensity distribution; a storage unit; a standard-waveform storing unit storing a first waveform of the signal including the peak point as a standard waveform in the storage unit; a waveform comparing unit comparing a second waveform of the signal with the standard waveform at fixed timing, wherein the standard-waveform storing unit stores a new waveform of the signal outputted by the light-receiving unit as the standard waveform in the storage unit in a case in which the second waveform is not equal to the standard waveform.
The above-described object of the present invention is also achieved by a method of correcting a positioning error of a light-receiving unit included in a coordinate input/detection device provided with a coordinate input area, the coordinate input/detection device including a light-emitting unit emitting a plurality of rays to the coordinate input area; the light-receiving unit receiving the plurality of rays reflected by sides of the coordinate input area, thereby obtaining intensity distribution of the plurality of rays, and outputting a signal corresponding to the intensity distribution; a standard mark provided at a fixed position in the coordinate input area so that the light-receiving unit generates a peak intensity corresponding to a ray reflected at the standard mark in the intensity distribution; a coordinate detection unit detecting coordinates of a pointing instrument inserted to the coordinate input area, in accordance with a position of the peak intensity in the intensity distribution; and a storage unit, the method including the steps of storing a first waveform of the signal including the peak point as a standard waveform in the storage unit; comparing a second waveform of the signal with the standard waveform at fixed timing; and storing a new waveform of the signal outputted by the light-receiving unit as the standard waveform in the storage unit in a case in which the second waveform is not equal to the standard waveform.
The above-described object of the present invention is also achieved by a recording medium readable by a coordinate input/detection device, tangibly embodying a program of instructions executable by the coordinate input/detection device to correct a positioning error of a light-receiving unit included in the coordinate input/detection device provided with a coordinate input area, the coordinate input/detection device including a light-emitting unit emitting a plurality of rays to the coordinate input area; the light-receiving unit receiving the plurality of rays reflected by sides of the coordinate input area, thereby obtaining intensity distribution of the plurality of rays, and outputting a signal corresponding to the intensity distribution; a standard mark provided at a fixed position in the coordinate input area so that the light-receiving unit generates a peak intensity corresponding to a ray reflected at the standard mark in the intensity distribution; a coordinate detection unit detecting coordinates of a pointing instrument inserted to the coordinate input area, in accordance with a position of the peak intensity in the intensity distribution; and a storage unit, the program including the steps of storing a first waveform of the signal including the peak point as a standard waveform in the storage unit; comparing a second waveform of the signal with the standard waveform at fixed timing; and storing a new waveform of the signal outputted by the light-receiving unit as the standard waveform in the storage unit in a case in which the second waveform is not equal to the standard waveform.
The coordinate input/detection device compares a waveform of a signal corresponding to intensity distribution of rays received from the coordinate input area by the light-receiving unit and a standard waveform at fixed timing. If the waveform is not equal to the standard waveform, the coordinate input/detection device determines that an installation position of the light-receiving unit is off a correct position because of shock or vibration, and obtains a new standard waveform and stores the new standard waveform in the storage unit, thereby setting the waveform of the signal corresponding to the intensity distribution of rays received by the light-receiving unit located at an incorrect position as the standard waveform. Accordingly, there is no error in relative positions of a peak point corresponding to the standard mark, that is, a standard for detecting coordinates of a pointing instrument in the coordinate input area, and a peak point corresponding to the pointing instrument in the intensity distribution, thereby preventing misdetection of the coordinates.
Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.